1. Field of the Invention
The present invention relates to an image combining apparatus for combining a plurality of images. In particular, the present invention relates to an image combining apparatus, an image combining method, and an image combining program that are suitable for use in a colorimetry apparatus for performing colorimetry of teeth, skin, and so forth.
This application is based on Japanese Patent Application No. 2005-365215, the content of which is incorporated herein by reference.
2. Description of Related Art
In recent years, there has been increased interest in beauty and health. In the beauty industry, for example, whitening for reducing melanin pigment in the skin has become a fashionable unit in the pursuit of beauty.
Skin-diagnosis camera systems which are designed to allow observation of magnified images of the skin surface on a monitor are used in conventional skin diagnosis; for example, they are used in dermatology, aesthetic salons, beauty counseling, and so on. In the case of dermatology, for example, by observing images of the grooves and bumps in the skin, features of the skin surface can be diagnosed and counseling can be given.
In the field of dentistry, dental treatments such as ceramic crowns are another aspect of the pursuit of beauty. The procedure for applying ceramic crowns involves first preparing a crown (a prosthetic tooth crown made of ceramic) having a color that is close to the color of the patient's original tooth, and this crown is then overlaid on the patient's tooth.
Conventionally, crowns are prepared by the process described below.
First, in a dental clinic, a dentist or other person acquires an image of the oral cavity of a patient. More specifically, images of the whole oral cavity including a plurality of teeth, the surface of a patient's vital tooth used as a reference for the crown preparation, and the like are acquired.
Subsequently, from a plurality of tooth samples having different colors (hereinafter referred to as “shade guides”), the dentist selects a shade guide that is closest to the color of the patient's vital tooth (this procedure is referred to as a “shade take” below). The shade guides are, for example, tooth-shaped samples that are made of ceramics of a plurality of different colors.
Upon completion of the procedure described above, the dentist sends the acquired images and a specific identification number associated with the shade guide selected in the shade take to a dental laboratory that makes crowns. Then, the crown is produced in the dental laboratory on the basis of this information.
However, the shade take described above has a problem in that it is not entirely quantitative because it depends on the subjective judgment of the dentist. Also, the appearance of the shade guide and the patient's tooth color may differ depending on various factors, such as the color tone of the gums, the environmental conditions, the illumination (for example, the illumination direction and color), the level of fatigue of the dentist, and so on. Therefore, it is very difficult to select the optimal shade guide, which places a significant burden on the dentist.
Consequently, in order to reduce the above burden on the dentist or other person, apparatuses providing support in procedures such as the shade take have been proposed; in such apparatuses, for example, a shade guide that is closest to the color of the patient's vital tooth is automatically selected.
For example, Publication of Japanese Patent No. 3710802 discloses a technique including storing in a computer in advance a data table in which identification information data of a plurality of tooth reference colors corresponds to color information data of the tooth reference colors in the L*a*b* calorimetric system, inputting image data prepared by simultaneously acquiring a vital tooth and reference samples (corresponding to the above “shade guides”) having the tooth reference colors, calculating a color correction value for substantially matching the color information data of the tooth reference colors of the reference samples in the L*a*b* calorimetric system analyzed in the image data with the color information data of tooth reference colors in the data table corresponding to the identification information data of the tooth reference colors to correct the color of the vital tooth, and extracting from the data table identification information data of a tooth reference color of color information data that corresponds to or that is similar to color information data of the corrected color of the vital tooth and outputting the extracted data.
However, in the invention disclosed in Publication of Japanese Patent No. 3710802, since the comparison results of the color of the vital tooth and the reference color etc. are expressed by numerical values, it is difficult for a user to intuitively understand the degree of color difference.